The present disclosure relates to conferencing applications involving exchange and annotation of video and, specifically, to techniques for mitigating aberrant rendering artifacts induced by communication delay among conference participants.
Conferencing applications are becoming increasingly popular tools in modern computing applications. Video conferencing applications, which once were cost-prohibitive for all except perhaps the largest of enterprises, now are widely available to the ordinary consumer. Now, many personal computers, laptop computers, tablet computers and smart phones come equipped with cameras and video conferencing applications that support real time video conferencing over the Internet.
The inventors desire to increase the capability of such conferencing applications. In particular, the inventors desire to add functionality that allows recipients of streamed video to make annotations to the video and share them with other conference participants. Such functionality adds complications, however, because, at the time a recipient adds an annotation to a frame being displayed at the recipient's device, that frame no longer is being displayed at the device from which it originated. Instead, the frame has been replaced by another frame at the originating terminal.
Processing delays are induced between terminals by various factors, including video compression, transmission and decompression operations. In the case of video streamed from one device to another, these delays cause a given frame (such as the frame that will be annotated) to be displayed then removed from an originating device before it is displayed at a receiving device. Network transmission can be a major contributor to such delays. Processing delays also cause delay in transmission of annotation data from a receiving device to an originating device. Thus, when an annotation is rendered at an originating device, it may appear to be out of sync with respect to the video it is intended to reference.
Accordingly, the inventors perceive a need in the art for techniques that support annotation to video data that is streamed between devices even in the presence of communication delays among such devices.